Using WinPcap to get TCP Data

I want to use WinPcap to write the data inside the TCP-Pakage into an array.

For that i read the WinPcap tutorial and some source codes from sourceforge.net. Until now i can choose the Network adapter and see packetsizes. I also integrated an filter on a special port.
Now i want to have the data written into an array, if possible always 2nibble (byte) into one array field. I know how to build the array with the size of tha data package coming, but how do i get the data unside the array?

Some more Information:
Using Win Xp and Visual Studio 2008. My c++ skills are not the best, but should be ok. The protocol i want to sniff is non official one, but it is after TCP/IP, so if i can ignore the headers of ethernet and TCP/IP und only get the data after that, this would be nice. If there is an solution to kumb into tha datafield after the tcp-header, htis would be better i think.

My probem is, i don't knwo how to start with that. First time using WinpCap.
My code as it is now: